Facile synthesis of graphene/polypyrrole 3D composite for a high‐sensitivity non‐enzymatic dopamine detection

One kind of nanocomposite consisting of graphene and polypyrrole was synthesized via a facile and mild way with the assistant of microwave irradiation. The synthesis route was embedding the polypyrrole into the graphene flakes to form a 3D structure, to achieve larger active surface and higher electro‐catalysis property. Structures and components of the composite were measured by X‐ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. A stronger electrochemical response of electrode with modified resultant was observed in the electrochemical test. Dopamine sensor based on the composite showed a sensitivity of 363 μA mM ^?1 cm^?2, a linear range of 1 × 10^?4 M to 1 × 10^?3 M , and a detection limit of 2.3 × 10^?6 M (S/N = 3). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44840.     

Disposable potentiometric citrate sensor based on polypyrrole‐doped films for indirect determination of sildenafil in pharmaceuticals formulations

A new sensitive and selective disposable potentiometric sensor based on polypyrrole (PPy) films for determination of sildenafil citrate (SC) was proposed. The pyrrole polymerization was performed in presence of citrate ions under galvanostatic conditions which resulted in a membrane of PPy doped with citrate anion at graphite pencil electrode surface. Experimental conditions (e.g., pH and conditioning time) and instrumental parameters (e.g., current density and electrical charge) were evaluated in order to reach the best potentiometric response for the proposed sensor. Under optimized conditions, the device presented a linear dynamic range (LDR) for citrate ions concentrations varying from 0.034 to 1.7 mmol L^?1 with a Nernstian slope of 57.2 mV dec^?1 and a limit of detection (LOD) of 30 µmol L^?1. The developed potentiometric sensor was applied for sildenafil citrate (SC) determination (pharmaceutical formulations) and results compared with an official spectrophotometric method indicating a good agreement for a confidence level of 95%. Effect of concomitants species on the potentiometric response of the proposed device and morphologic characterization using microscopy of atomic force (AFM) were realized. The surface roughness of PPy films (synthesized in citrate solution and chloride) showed poorly affected by changing the doping anion, probably because the polypyrrole nodules grow three‐dimensionally simultaneously. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43762.     

Electrosynthesis,characterization, and application of poly(3,4‐ethylenedioxythiophene) derivative with a chloromethyl functionality

Poly(2‐chloromethyl‐2,3‐dihydrothieno[3,4‐b][1,4]dioxine), a chloromethyl functionalized poly(3,4‐ethylenedioxythiophene) derivative (PEDOT‐MeCl), was synthesized electrochemically via the potentiostatic polymerization of its monomer in dichloromethane solution containing suitable tetrabutylammonium tetrafluoroborate, then it was used for the characterization of film properties and the fabrication of electrochemical sensor. The properties of the resulting PEDOT‐MeCl film were characterized by different methods such as cyclic voltammetry, electrochemical impedance spectroscopy, Fourier transform infrared and ultraviolet–visible techniques, scanning electron microscope, and thermogravimetric analysis. The PEDOT‐MeCl film displayed a good reversible redox activity, remarkable capacitance properties, good thermal stability, rough, and porous structure, especially fluorescent spectra indicated that PEDOT‐MeCl was a blue‐emitter with maximum emission centered at 396 and 398 nm. Finally, the PEDOT‐MeCl film was employed for the fabrication of the sensing electrode, and dopamine was chosen as a model analyte for the application of the electrochemical sensor. Results indicated that the PEDOT‐MeCl film as sensing interface was feasible, and studies of these film properties were very beneficial for studying properties and applications of other poly(3,4‐ethylenedioxythiophene) derivative films. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2660–2670, 2013     

Gold nanoparticle patterned on PANI nanowire modified transducer for the simultaneous determination of neurotransmitters in presence of ascorbic acid and uric acid

In the present work, we have electrochemically deposited polyaniline nanowires (PANIS) on glassy carbon electrode (GCE) from its monomer liquid crystalline template of anilinium‐3‐pentadecyl phenyl sulphonic acid (An⁺ PDPSA^?). Further, electrode was modified by the electrochemical patterning of gold nanoparticles on the PANIS/GCE (PANIS/Au/GCE) by electrodeposition through chronoamperometry. Modified electrode characterized by electrochemical impedance, morphology, XRD, electroactive surface area, and later demonstrated its efficacy for the individual and simultaneous sensing of dopamine, ascorbic acid, serotonin, and uric acid. Finally, its performance in the real sample (blood serum) was evaluated. The superior electrocatalytic performance with higher sensitivity suggested that the modified electrode can be used as an excellent transducer for the sensing of neurotransmitters. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 44351.     

Enhancement of polyaniline properties by different polymerization temperatures in hydrazine detection

In this study, a simple and cost effective chemical sensor for hydrazine detection was developed using polyaniline (PAni). PAni was synthesized via chemical oxidative method at different polymerization temperatures (?10, ?5, 0, and 25°C) in the presence of sodium dioctyl sulfosuccinate (AOT) as dopant. The effect of polymerization temperature on the performance of the PAni sensor for hydrazine detection was evaluated. The sensor response was analyzed using UV–Vis spectrometer, where there is notable decrease in polaron peak at ～780 nm after the PAni was exposed to hydrazine. The reduction in the polaron peak is attributed to the decrease in the conductivity of PAni thin films owing to dedoping process by hydrazine. Fourier transform infrared analysis was carried out to study the intensity ratio of quinoid/benzenoid peak to identify the changes in chemical structure of PAni upon exposure to hydrazine. Besides that, all PAni sensors synthesized at different polymerization temperatures showed good reusability up to 10 cycles with respond and recovery time of 0.12 min and 0.08 min, respectively. Data collected in this study indicate that PAni which was synthesized at ?5°C could act as sensitive sensor for hydrazine detection with a detection limit of 0.24 ppm. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41746.     

Fabrication of self-functionalized polymeric surfaces and their application in electrochemical acetaminophen detection

Conducting polymer coatings have offered functionalized surfaces having good electrical, mechanical, and physical properties. In this work, electrochemical preparation and characterization of polypyrrole/polypyrrole-3-carboxylic acid (PPy/PPa) copolymer onto single-use pencil graphite electrodes (PGEs) were described and detailed. Then, the application of these electrodes was demonstrated for the detection a commonly used analgesic, acetaminophen (AC) (paracetamol). Copolymer was deposited onto PGEs using cyclic voltammetry (CV) between +0.0 V and +1.0 V versus Ag/AgCl. Experimental conditions such as the effect of monomer ratios (3:1–6:1) and cyclic scans (1 cycle to 10 cycles) on electropolymerization were examined. Coated surfaces were characterized with CV and scanning electron microscopy. Electrochemical response of the electrode in AC at various pH values was evaluated. Then, AC detection was performed based on the oxidation signal of the drug at about +0.55 V versus Ag/AgCl using differential pulse voltammetry in buffer and body fluid (serum).     

A highly selective electrochemical sensor for l‐tryptophan based on a screen‐printed carbon electrode modified with poly‐p‐phenylenediamine and CdS quantum dots

A new highly selective electrochemical sensor for the determination of l ‐tryptophan was proposed by modifying the surface of screen‐printed carbon electrodes (SPCEs). The surface of SPCE was firstly modified by electropolymerization of p‐phenylenediamine (PPD). The polymer film was then covalently linked with cysteamine capped cadmium sulfide quantum dots (Cys‐CdS QDs) by using glutaraldehyde (GA) as a cross‐linker resulted in an organic–inorganic hybrid composite film (QDs/GA/PPD/SPCE). The modified electrode was applied as a working electrode for detecting various amino acids. It was found that the modified electrode gave an electrochemical response selectively to l ‐tryptophan over other amino acids. The experimental parameters, including pH of solution, buffer types, electropolymerization cycles, scan rate, and accumulation time, were studied and optimized. The proposed sensor can be used to detect l ‐tryptophan with a low detection limit of 14.74 µmol L^?1 with good precision and the relative standard deviation less than 3.7%. The modified electrode was used to detect l ‐tryptophan in beverage samples and gave satisfactory recoveries from 91.9 to 104.9%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40356.     

Electrochemical inspection of polypyrrole/chitosan/zinc oxide hybrid composites

Polymer nanocomposite composed of polypyrrole, chitosan, and zinc oxide nanoparticles has been synthesized and it has been evaluated for various electrochemical aspects of the current electrochemical industry. The polypyrrole (PPy) was synthesized by the chemical oxidative polymerization reaction by employing ammonium persulfate as oxidizing agent. Composites of polypyrrole/chitosan (PPy/Chy) and polypyrrole/chitosan/ZnO (PCZ) composites were synthesized by the solution blending method. Detailed structural, morphological, thermal characterization of PPy, PPy/Chy, and PCZ were performed to characterize the specific features of the systems. The composites exhibit better thermal stability and high surface area and the addition of ZnO nanoparticle increase the crystallinity of the composite. Electrochemical characterization of the ITO electrodes modified with PPy, PPy/Chy, and PCZ were performed using cyclic voltammetry, electrochemical impedance spectroscopy, and amperometry techniques. The present study highlights the role of a bio-compatible material with high surface area and conductive constituent for designing of various high performing electronic noninvasive sensors, biosensors, and so forth.     

Piezoelectric coaxial filaments produced by coextrusion of poly(vinylidene fluoride) and electrically conductive inner and outer layers

The development of new thermoplastic polymer‐based piezoelectric sensors with filament geometry is described. These filaments are appropriate for integration into textiles and provide new possibilities in the design and development of low‐cost flexible sensors produced at high rates. The developed three‐layered piezoelectric monofilaments have been produced by coextrusion using poly(vinylidene fluoride) and two different polypropylene‐based electrically conductive polymers. Filaments with about 800‐µm diameter, producing electrical signals proportional to the mechanical deformation applied, were obtained. The signal output has been found adequate for straightforward use with conventional piezoelectric signal conditioning systems. One of the conductive polymers tested allowed better filament geometry and process stability. This article describes the coextrusion production process and the results obtained in the electromechanical tests performed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40710.     

Oxidative solution polymerization of aniline hydrochloride onto electrospun nanofibers mats of polylactic acid: Preparation method and characterization

In this work, we present the preparation of polylactic acid (PLLA)/polyaniline (PANI) conductive composite nanofibers mats. They are prepared by bulk oxidative solution polymerization of PANI onto electrospun non‐woven fibers mats of PLLA. The PANI ratio in the composite is about 70%w/w. Scanning electron microscopy (SEM) shows that PLLA nanofibers are randomly oriented, beads free with diameters of 186 ± 85 nm, The PLLA/PANI composite nanofibers diameter values are 518 ± 128 nm with a good adherence between PANI and PLLA nanofibers. DSC and XRD measurements reveal an amorphous structure of the electrospun PLLA fibers due to the rapid evaporization of the solvent. FTIR and UV–vis spectra reflect good mutual interactions between PANI and PLLA chains. The DC‐conductivities ( ) far better than other published ones for similar composites prepared by bulk oxidative solution polymerization of PANI onto other electrospun nanofiber mats or with electrospun nanofibers from a solution mixture of PLLA and PANI. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41618.     

Influence of monomeric concentration on mechanical and electrical properties of poly(styrene-co-acrylonitrile) and poly(styrene-co-acrylonitrile/acrylic acid) yarns electrospun

Two series of copolymers were synthesized by emulsion polymerization: poly(styrene-co-acrylonitrile) P(S:AN) and P(S:AN-acrylic acid) P(S:AN-AA). The monomeric concentrations in both series were: 0:100, 20:80, 40:60, 50:50 (wt%:wt%), and 1 wt% of AA. The copolymers were dissolved in N,N-dimethylformamide (4–10 wt%) and were electrospun. Polymeric yarns were collected using a blade collector. The synthesized and fabricated materials were characterized by known techniques. Mechanical and electrical properties of polymeric yarns indicated a dependence of monomeric concentration. Elastic modulus increases as acrylonitrile concentration increases (up to 30 MPa). Yarns were submitted to degradation process into saline solution, where the acrylic acid content kept a constant elastic modulus at long times. The electrical current into yarns was higher when the concentration is 50:50 wt%:wt% (1.2 mA). The cytotoxicity results showed a cell viability close to 100% for yarns without AA.     

Aniline‐nonamer segmented polyurea: A facile electrocatalyst for detection of ascorbic acid

An unprecedented A‐B‐A type block copolymer electroactive polyurea (EPU) is designed and synthesized with tetraaniline dimer and 1,4‐phenylenediamine via an oxidative coupling, where aniline–nonamer and hexamethylene di‐urea constitute two segments. The EPU was characterized by spectral techniques such as Fourier transform infrared spectroscopy, nuclear magnetic resonance, and UV–vis spectra. The structural characterization of the prepared EPU was obtained by powder X‐ray diffraction and X‐ray photoelectron spectroscopy techniques. EPU reorganizes into core–shell microcapsules in presence of aqueous acetic acid/n‐octane interface. These microcapsules exhibited a wide range of pH responses in their absorption spectrum (UV–vis). The EPU is modified as carbon paste electrode which exhibits a remarkable electrocatalytic oxidation of ascorbic acid (AA, Vitamin C) in 0.2 M and pH 7.0 phosphate buffer solution. The carbon paste electrode is useful in sensing as low as 50 µM of ascorbic acid. This can open up new opportunities for fast, simple detection of AA providing a promising platform for sensor/biosensor designs for AA detection. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46630.     

Smart films based on bacterial cellulose nanofibers modified by conductive polypyrrole and zinc oxide nanoparticles

In this study, we synthesized novel films based on bacterial cellulose (BC), BC modified by polypyrrole (PPy), and a PPy–zinc oxide nanocomposite (BC–PPy–ZnO). The soft polymerization method at room temperature was used to obtain the BC–PPy and BC–PPy–ZnO films. The Combined D‐Optimal design was used to study the effects of the pyrrole monomer concentration, ZnO concentration, and polymerization time on the morphological, physical, color, and electrical conductivity properties of the films. Fourier transform infrared results reflected that some new interactions occurred between BC and PPy and PPy–ZnO. The X‐ray diffraction analysis showed that the crystalline behavior of the BC fiber was hindered because of the complete coating with the amorphous PPy particles. Scanning electron microscopy results show that the ZnO, PPy, and PPy–ZnO nanoparticles were placed between the BC fibers. PPy decreased the water vapor permittivity and total soluble matter percentage. Electrical conductivity studies of the synthesized BC–PPy–ZnO film showed that the film's electrical resistance was changed in different oxidation–reduction or volatile compounds media, so the results suggest that the BC–PPy–ZnO films could be used in antioxidative food active packaging and smart packaging. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46617.     

Polypyrrole-coated fiber-scaffolds: Concurrent linear actuation and sensing

Conducting polymers such as polypyrrole (PPy) can be deposited on various substrates to obtain conductive electroactive coatings. While electrochemical coatings are generally considered to be more effective, chemical coatings are more industrially suitable, especially on complex substrates. In this work, we aimed to explore the electro-chemo-mechanical response of conductive fiber scaffolds (CFS) prepared by coating PPy (chemically) on glucose-gelatin nanofibre scaffolds. Electroactivity was readily observed in both aqueous and propylene carbonate solutions of lithium bis(trifluoromethanesulfonyl)imide, with mainly anion activity in both cases. A higher actuation response was achieved in the aqueous solutions with strain in the range of 1.2% and stress in the range of 3 kPa. Under both cyclic voltammetry and square wave potential steps driving, stable actuation for over 100 cycles was maintained. In addition to actuation, the CFS samples exhibited concurrent sensory properties, in sensing current densities and mechanical load. The PPy-coated CFS material functioning as both an actuator and a sensor is envisaged to have potential applications in smart materials, soft robotics or e-skin. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48533.     

Electrical properties and the role of inhomogeneities at the polyvinyl alcohol/n‐inp schottky barrier interface

In this work, we have investigated the electrical properties of Au/n‐InP contacts with a thin layer of polyvinyl alcohol (PVA) as an interlayer. The current–voltage (I–V) and capacitance–voltage (C–V) measurements are carried out in the temperature range of 175–425 K. The Au/PVA/n‐InP Schottky structure show nonideal behaviors and indicates the presence of a nonuniform distribution of interface states. The temperature dependent interface states densities (N_SS), ideality factor and barrier height are obtained. An abnormal decrease in zero‐bias barrier height (BH) and increase in the ideality factor ( ) with decreasing temperature have been explained on the basis of the thermionic emission theory with Gaussian distribution (GD) of the BHs due to the BH inhomogeneities. The experimental I–V characteristics of Au/PVA/n‐InP Schottky diode has revealed the existence of a double GD with mean BH values of ( ) of 1.246 and 0.899 eV and standard deviation ( ) of 0.176 and 0.137 V, respectively. Consequently, the modified conventional activation energy versus plot gives and Richardson constants ( ) and the values are 1.17 and 0.71 eV and 9.9 and 6.9 A/cm² K², respectively, without using the temperature coefficient of the BH. The effective Richardson constant value of 9.9 A/cm² K² is very close to the theoretical value of 9.4 A/cm² K² for n‐InP. The discrepancy between Schottky barrier heights estimated from I–V and C–V measurements is also discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39773.     

Freestanding chemiresistive polymer composite ribbons as high-flux sensors

Chemiresistive polymer composite ribbons that function as chemical detectors were produced from solution-cast films of polymers and carbon composites. An array with multiple polymer sensor threads was exposed to dimethyl methyl phosphonate, a nerve agent simulant, and different interferents in the vapor phase. Principal component analysis was used to differentiate between the analytes. The response of the ribbon sensors as a function of the carbon composite and the host polymer source was investigated. The freestanding threads/sensors were mounted into a cell perpendicular to the gas flow to provide little pressure drop and were imbedded into fabrics to provide an example of a small, low-cost, wearable chemical sensor. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Piezoelectric polymer microfiber-based composite for the flexible ultra-sensitive pressure sensor

This study presents a new type of composite consisting of piezoelectric poly(γ-benzyl-α, l -glutamate) (PBLG) polymer fibers, which contain a large dipole moment, and the elastomer polydimethylsiloxane (PDMS) as the matrix material. PBLG microfibers were fabricated and polarized using the electrospinning method and cast in PDMS to form a unidirectional continuous-fiber composite. The PBLG/PDMS composite was characterized based on various aspects such as crystalline structure, mechanical properties, piezoelectricity, and electromechanical response. The piezoelectric charge constants in the transverse and longitudinal modes were measured to be 10.2 and 54 pC/N, respectively, which are the largest piezoelectric coefficients of biocompatible polymers up to date. The thin PBLG/PDMS composite film can produce up to 200 mV peak-to-peak under sinusoidal actuation and exhibit ultra-sensitivity up to 615 mV N⁻¹. These results show the great potential of the highly flexible piezoelectric polymer fiber-based composite for use in a variety of applications such as energy harvesting devices, biomechanical self-powered structures, and force sensors. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48884.     

Economical conductive graphite-filled polymer composites via adjustable segregated structures: Construction,low percolation threshold,and positive temperature coefficient effect

The economical graphite-filled thermoplastic urethane/ultra-high molecular weight polyethylene (TPU/UHMWPE) composites with the segregated structure were constructed by the combination of mechanical crushing and melt blending method. The low percolation threshold of 1.89 wt% graphite in the adjustable segregated composites was obtained and high electrical conductivity was about 10⁻¹ S m⁻¹ at 10 wt% graphite loadings owing to the formation of three-dimensional conductive networks. Moreover, when the graphite loadings were over the percolation threshold, the remarkable positive temperature coefficient (PTC) effect of electrical resistivity for TPU/UHMWPE-Graphite composites were achieved, originating from the combined thermal motion of TPU and UHMWPE. Meanwhile, the outstanding repeatability of PTC effects was obtained after 5-time cycles. Therefore, economical conductive polymer composites were still the promising field in the practical application of PTC materials.     

Effect of polymer matrix on the performance of pressure‐sensitive paint comprising 5,10,15,20‐tetrakis(pentafluorophenyl)porphinato platinum(II) and poly(1,1,1,3,3,3‐hexafluoroisopropyl‐co‐tert‐butyl methacrylates)

Copolymers of 1,1,1,3,3,3‐hexafluoroisopropyl methacrylate (HFIPM) and tert‐butyl methacrylate (TBM) were prepared by conventional radical copolymerization as a novel binders for pressure‐sensitive paints (PSP). The monomer reactivity ratios r_HFIPM and r_TBM were determined as 0.45 and 0.67, respectively. The glass transition temperature of the copolymers increased from 77 to 126°C with increasing mole fraction of TBM units in the copolymer. The PSP were formed by combining the resulting copolymers and 5,10,15,20‐tetrakis(pentafluorophenyl)porphinato platinum(II). The pressure and temperature sensitivities of the PSPs were measured at air pressures ranging from 5 to 120 kPa and at temperatures ranging from 0 to 60°C. Modified Stern–Volmer plots indicated slight increases in the pressure sensitivity, but significant decrease in the temperature sensitivity as the mole fraction of HFIPM units increased in the copolymer. Applying a theoretical model to our calibration data, we inferred that luminescence quenching is primarily responsible for increasing the temperature sensitivity in the resulting copolymers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43316.     

Room temperature CO sensing by polyaniline/Co3O4 nanocomposite

Polyaniline/cobalt oxide (PANI/Co₃O₄) nanocomposites have been investigated for their sensitivity towards carbon monoxide (CO) gas at room temperature. The Co₃O₄ nanoparticles were prepared by ultrasound assisted coprecipitation method and then incorporated into the PANI matrix. Fourier transform infrared spectroscopy and ultraviolet–visible spectroscopy, powder X‐ray diffraction, and field emission scanning electron microscopy have been used to characterize the nanomaterials. The PANI/Co₃O₄ nanocomposite sensors were found to be highly selective to CO gas at room temperature. A significantly high response of 0.81 has been obtained for 75 ppm CO concentration with a response time of 40 s. Based on the observations of the sensing study, a mechanism for CO sensing by the nanocomposite has been proposed. Influence of humidity on the sensor response towards CO has also been studied and the results presented. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44115.